It is one of the best and tastiest ways to introduce more fibre into our daily routine, beating inflammation and strengthening bones, researchers say.

Fatty acids produced as a by-product when gut bacteria break down fibre can protect against rheumatoid arthritis and other autoimmune diseases.

Exactly how the bacteria and the immune system communicate is still unclear.

But researchers believe their findings are be a positive step in fi nding new ways to combat autoimmune disease. 

“We were able to show that a bacteria-friendly diet has an anti-inflammatory effect, as well as a positive effect on bone density,” explained Dr Mario Zaiss, who led the team behind the study.

“Our findings offer a promising approach for developing innovative therapies for infl ammatory joint diseases as well as for treating osteoporosis, which is often suffered by women after the menopause.

“We are not able to give specific recommendations for a bacteria friendly diet at the moment, but eating muesli every morning as well as enough fruit and vegetables throughout the day helps to maintain a rich variety of bacterial species.”

The findings, from Friedrich-Alexander University in Germany, won applause from experts yesterday who hailed it for adding much needed detail to the growing body of evidence showing the benefits of a good diet. 

Dietician Catherine Collins said the new findings added to previous studies on mice which showed the positive effects of giving high levels of fermentable fibre to their diets.

Ageing mice experience similar problems to humans in bone loss and inflammatory disease.

“The bottom line is that this is adding to existing research that shows that our gut bacteria and what we eat can influence our bone health.”

It was already known that a wide variety of foods in the diet creates a diverse microbiome – the colony of beneficial gut bacteria – that is considered best for health.

“This study suggests a link with the amount of fibre we eat,” she added.

 “Including fibre-rich foods daily will help boost healthy bacteria levels in your bowel. Fibre-rich foods are all plant-based, and are an important part of a healthy diet, especially a Mediterranean-style, so enjoy.”

What is exciting experts is the potential the new findings offer for preventing bone breakdown and boosting bone replacement.

Inflammatory damage such as that in rheumatoid arthritis, or the acceleration of bone loss during and just after the menopause, compromises bone health and strength, and may lead to easily broken bones.

Rheumatoid arthritis causes widespread inflammation across the whole body.

Inflammation is known to interfere with the normal rebuilding processes and maintenance of bone. Previous studies involving mice showed that those who were fed a diet rich in fermented fibre were able to absorb some of it and use it to build bone tissue. 

In these mice, the levels of inflammatory cells were decreased and there seemed to be a positive influence on bone preservation by influencing the immune system and its potential to cause inflammation that interferes with normal bone turnover According to the National Rheumatoid Arthritis Society, about 1 per cent of the UK’s population, at least 400,000 people, has the autoimmune disease.

It affects roughly two to three times as many women as men.

The most common age for people to develop the debilitating condition is between 40 and 60, or slightly older for men.

There are other forms of inflammatory arthritis, but rheumatoid is the most common. If it is not treated it can cause irreversible damage to joints and lead to disability.

The research is published in the latest issue of the journal Nature Communication.